This application is directed to the art of pipe joints and couplings and more particularly to an internal joint or coupling construction for plastic pipe or tubing.
The invention is particularly applicable to connecting adjacent ends of corrugated plastic pipe or tubing lengths and will be described with particular reference thereto. However, it will be appreciated that the invention has broader applications and may be incorporated as an integral part of the tubing or may be sized and configured to accommodate connecting of different tubing sizes and/or alternate connecting applications.
Corrugated plastic pipe or tubing is widely used for many types of domestic, agricultural and industrial drainage systems. This pipe or tubing is typically molded from high density polyethylene and polyvinylchloride and is generally supplied in continuous lengths. These lengths may be connected together and/or cut into shorter lengths for meeting particular installation needs. The pipe itself is generally cylindrical and has corrugated internal and external wall surfaces defined by adjacent circumferentially extending, longitudinally spaced peaks and valleys over the lengths thereof.
When installing such pipe or tubing in the ground for drainage purposes, it is oftentimes necessary to connect the ends of two pipe lengths during the process. Heretofore, there have been many different types and styles of joints or couplers which have been developed for this purpose. Particular emphasis has been placed on making these joints and couplings simple in construction to facilitate ease of assembly and cost savings. Simplicity of assembly reduces the time necessary to lay drainage pipe and, therefore, its effective cost. If a number of manipulations are necessary to physically connect the adjacent pipe ends, the overall cost of the installation will be increased. Such cost increases can become particularly significant when laying a substantial length or amount of such pipe.
Prior joints or couplings have typically comprised the so called external type couplers which fit on the outside of the lengths of pipe at the joint area. Many external coupler designs have been developed and introduced for practical application. Some of these comprise wrap around types which fasten with snap buttons, belts or the like. Spiral tubing manufacturers utilize a screw on swivel type of coupler which snaps together. Still other designs have comprised so-called split type couplers which require being wrapped with tape, twine or wire.
While many of these external couplers have proved reasonably successful in accomplishing the intended results, they do have certain inherent difficulties which detract from their use in automatic pipe laying machines. That is, many external couplers are too large in diameter to pass through the feeding devices on most such machines. Indeed, and especially with high speed drain tube type plows, the external couplers are often damaged so that there is a loss of integrity in the joint between the two tubing sections and/or these sections may be uncoupled during the installation process. With split type coupler designs, the feeding process often rips the tape or twine such that the coupler can become unfastened. Moreover, wrapping twine, snapping buttons and fastening belts all require additional assembly time for making up the joint in the first instance.
There have also been some prior development efforts directed to incorporating integrally molded internal and/or external coupling arrangements in the tubing as it was molded. Typically, such integrally formed coupling arrangements were disposed at repetitive spaced apart distances along the tubing length and included special structural provisions and designs for both the male and female coupling components. Because of the specialized nature of the coupling component designs, they necessarily require special and intricate molds which, in turn, increase cost for the tubing manufacture and installation.
It has been found desirable to eliminate the above noted problems with prior coupling arrangements through development of an internal coupler structure. To that end, the present invention contemplates a new and improved internal coupling arrangement which is simple, economical, facilitates the positive locking of adjacent lengths of pipe, has a self actuating feature which enhances the coupling strength when a pull force is applied thereagainst, permits adjacent lengths of pipe to be bent at sharp angles to each other without disturbing the integrity of the joint, which does not adversely affect the fluid flow capacity of the pipe, and which is readily adapted to use for a number of alternative applications in the same or different environments.